The invention relates to a signal converter circuit for processing a sensor signal into an output signal, the circuit comprising a sensor connection for receiving a sensor signal, further comprising two comparator circuits, each having a signal input for an electric connection to the sensor connection, a reference input for an electric connection to a respectively assigned reference signal source and a signal output for a provision of an output signal, with a feedback line being formed between the respective signal output and the respective reference input, and further comprising two reference signal sources, each of which is configured to provide a reference signal, each of the comparator circuits being configured to compare a signal level at the signal input to a signal level at the reference input and for outputting a digital output signal as a function of a comparison result between the signal levels. The invention further relates to a method for evaluating a sensor signal of a safety-oriented device.
From German Patent Application DE 1 499 505, which is published for opposition, a monitoring device for a redundant circuit arrangement is known, in which between two transmission lines there is in each case connected a comparison element, at the output of which an alarm switching device connected to all comparison elements is provided; this responds if the output signal of at least one comparison element exceeds a preset limit value, wherein an alternating voltage is used for the control signal and a differential amplifier serves as a comparison element, wherein the output of the differential amplifier is connected to a bistable circuit at the output of which the alarm switching device connected to all bistable circuits is switched, and wherein a connecting line with two branches, the first of which branches, which contains a diode, is connected to a first input of the bistable circuit, and the second of which branches, which contains a parallel circuit of a capacitor and a Zener diode, is connected to a second input of the bistable circuit, is located between the differential amplifier and the bistable circuit, and wherein a reverse bias lower than the breakdown voltage of the Zener diode is applied to the diode.